this is a program that can be used to play quake demos ranging from qw, q2, q3
(you have to bear in mind thou that this program hasn't been worked on in ages... so it only supports dm3 files for q3 and not sure what it supports in qw or such)
here is the link to the website is
but i think its down as devlopment stopped a while ago.

this utility has some nice features like being able to set demoplay to act as a screen saver and play some of your fav demo as your screensaver (nice feature if u ask me)